Metallic corrosion inhibition of polyhalogenated hydrocarbons with propargyldiisopropylamine



United States Patent M 2,997,507 METALLIC. CORROSION INHIBITION OF POLY- HALOGENATED HY DROC'ARBONS WITH -PRO- The present invention relates: to anticorrosion agents and antioxidants, and is more particularly-concernedwith prevention of corrosion and oxidation of and in, chlorinated aliphatic hydrocarbon solvents 'to obtain solvent compositions having improved stability at elevated temperatures and to chlorinated aliphatic hydrocarbon sol-* vents containing-an amine having the general formulaz bon solvents are unstable under heat, light, air and metal The field wherein all of these conditions are.

contact. found is the art of vapor degreasing. In the art of degreasing metals, fortexample, the chlorinated aliphatic hydrocarbons have been employed to the almost total exclusion of other solvents. These compounds, desirable because of their substantial high solvent action under the conditions of use and relative freeness from fire hazards, have major drawbacks, such as their instability under acid conditions. Mineral acids causethe degradationof the chlorinated hydrocarbon solvents, the degradation products including, in many instances, HCI. Thus,.

the degradation progresses in a somewhat chain-like manner to increase the acidity of the solution and thus catalyze further degradation: Further, long-chain fatty acids commonly introduced into the system by buffing compounds, cutting oils, etc., deplete the usual basic (amine) acid-acceptors thus permitting the mineral acids as formed'to cause further'de'gradation.

Itis, therefore, an object Ofthe present invention to provide an additive which when present in minor quantities in chlorinated hydrocarbon. solvents will prevent the degradation of the solvent. A further object is -to provide an additive which will prevent 'thecorrosiou of metal in contact with the solvents, thereby prolonging the useful life'of such solvents and the metal in contacttherewith. Another object is to provide an additive which in minor amounts will remain etfective in the chlorinated hydrocarbon solvents in both'the liquid and .vapor phases. A stillfurthenobjectis to provide an ingredient which will prevent corrosion and oxidation under acid conditions andmwhichmwillnnot be depleted by.the:-acid conditions. These and other objects will become apparent to those skilled in'theart from the following'speciticatio-n and: claims:-

It has now. been -found. thatusubstantial inhibition'iof the build-up'rofflacid the prevention a of 1 corrosion and oxidation, andi'the .protectionvof theusualstabiliiers em- Patented Aug. 22, 1961 wherein each R has the aforesaid significance, is added to chlorinated hydrocarbon solvent compositions. Further commercial solvents containing the usual additives,

such as, diisopropylamine, butylene oxide, isopropyl acetate and 2,4,4-trimethyl-2-pentene are effectively protected from acid buildup oxidation, corrosion and depletion of the inhibitors. Good results are obtained when the amine is employed in amounts of from 50 to 5,000 parts by weight per million parts of chlorinated hydrocarbon. An advantage of the amines of the present invention is that they are not immobilized or bound in the liquid phase but arefound in elfective concentration in both theliquid and vapor phase; Thus, corrosion is minimized in both phases, yet thecompound is not immobil-- ized as are the usual hydrogen chloride acceptors such as the saturated amines. The inhibitor of the present invention prevents the oxidation of the solvent in the presence of'air and/ or light, thus preventing the degradation of the solvent. The additives of the present invention are found to be eifectiveas antioxidants even after theidevelopment of more than stoichiometric quantitiesof H61 or other acids in 'the system.

Compounds which can be employed in the practice of the invention andifallingwithin the general formula are 3-dimethylamino-3methyl-l-butyne, 3-dimethylamino-1pentyne, allyldiisopropyl amine, triallylamine, diallypropylamine, allyldiethylamine, propargyldiisopropy] amine, and the'like.

The following examples are-illustrative of the present invention but are to be construed as limiting the same.

ACCELERATE D OXIDATION TEST ('MILT 7003) ACID ACCEPTANCE DETERMINATION AZO mlasam'ple of a typical commercial solvent formulation (as above described.) is refluxed for 5 minutes with an excess of alcoholic HCl over that required to react with the inhibitor. Thereafter, 25 ml. of Water is adddcontaining phenolphthalein. The formulation is back tritrated with standard NaOH solution.

determination 'is run before and after the accelerated" oxidation 'test on samples drawn from solvents used in that" tesc:

Percent" acid acceptance '-is calculated aspercent NaOH. This Examples 1 through 5 The above tests were carried out with solvent Formulation A, as set forth above, both alone and also with the indicated additives. The results tabulated below are determined before and after the accelerated oxidation test.

In the manner of Examples l-4, employing like solvent compositions except that the initial acid content was higher, the following results were obtained:

P.p.m. Acid as H01 Before After Trichloroethylene (A) 60 over 200 Trichloroethylene (A)+50O p.p.m. propargyl diisopropylamine .50 6

Example 7 A 50 ml. portion of the solvent composition of A containing 500 ppm. propargyldiisopropylamine was refluxed for 7 days with a 2 /2 inch x /2 inch metal tes-t coupon of one of the below-listed metals. The test was run simultaneously with a solvent mixture of trichloroethylene and 52 ppm. of propargyldiisopropylamine only. The results are tabulated below:v

Mils Penetration per Year Al Brass Cu Fe Zn A+500 p.p.m. propargyldiisopropylamine O. 00 0. 03 0. 01 0. O0 0. 70 Trichloroethylene+52 p.p.m. propargyldiisopropyla-mine 0. 51 0.78 0. 24

Example 8 A laboratory degreaser was run with a trichloroethylene solvent A+50O ppm. of propargyldiisopropylamine to which had been added 30 percent by volume of mineral oil for approximately 28 days with test plates of zinc, brass, iron and aluminum in the cooling coils, warm dip, and boiling sump. The solvent was found to have an acid acceptance equivalent to 0.50 percent of sodium hydroxide in the warm dip at the end of this run and the corrosion rate of the plates at the various points was negligible.

Example 9 Trichloroethylene containing 3000 parts per million, by weight of butylene oxide 2500 p.p.m. of ethyl acetate, 1500 p.p.m. of trimethylpentene and 500 p.p.m. of an amine Was treated with 10 pencent by weight of oleic acid. The solvent was distilled off and an accelerated oxidation test was run as disclosed above. The results of such tests are set forth below:

Acidity in p.p.m. before and after Accelerated Oxidation Test Before After Propargyl dilsopropylamine 23 Allyl diisopropylamine..- 23 50 Ethyl diisopropylamlne.-. 23 1 over 200 1 Titration stopped at 200.

It is thus apparent that halogenated hydrocarbon solvents may be stabilized against acid condition by employing the compounds of the present invention in the manner hereinbefore described. Solvents may be stabilized, in addition to trichloroethylene are, for example, carbon tetrachloride, ethylene dichloride, methyl chloroform, perchloroethylene and the like.

The compounds of the present invention have been shown to exhibit anticorrosion properties in both the vapor and liquid phases of the degreasing operation. Further, these compounds are recoverable with the solvent in clean-up operations.

This application is a continuation in part of our copending applications Serial Nos. 713,522 and 713,523 both filed February 6, 1958, both now abandoned.

We claim:

1. A stabilized halogenated aliphatic hydrocarbon solvent comprising from 50 to 5,000 parts by weight of a compound having the formula wherein the three Rs each represent a lower aliphatic hydrocarbon radical, at least one of them being unsaturated, the total number of carbon atoms in the three being from- 4 to 10 inclusive, per million parts by weight of solvent.

2. A solvent composition as set forth in claim 1 where in the compound is 3-dimethylamino-3-methyl-l-butyne. 3. A solvent solution as set forth in claim 1 wherein the compound is allyldiisopropylamine.

' 4. A solvent solution as set forth in claim 1 wherein the compound is propargyldiisopropylamine.

' 5. A stabilized trichloroethylene solvent comprising from 50 to 5,000 parts by Weight of a compound having the formula wherein the three Rs each represent a lower aliphatic References Cited in the file of this patent UNITED STATES PATENTS 2,043,257 Missbach June 9, 1936 2,160,944 Coleman et al. June 6, 1939 2,476,554 Lincoln et al. July 10, 1949 2,543,575 Harvey et al. Feb. 27', 1951 2,781,406 Dial Feb. 12, 1957 

1. A STABILIZED HALOGENATED ALIPHATIC HYDROCARBON SOLVENT COMPRISING FROM 50 TO 5,000 PARTS BY WEIGHT OF A COMPOUND HAVING THE FORMULA 